• Journal of Life Science
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• v.12 no.6
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• pp.682-687
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• 2002

We analyzed improvement on the enzyme activity of CPase Taq by addition of various metal ions. The enzyme activity was increased more then four times by 1 mM cobalt ion and almost three times by 1 mM calcium ion. However, the active center metal zinc ion did not affect the enzyme activity. In order to investigate whether the active center metal affects the enzyme activity, zinc ion which is occupied the active center of the enzyme was replaced by cobalt ion which activates the enzyme activity very effectively. Since the cobalt ion in the active center of the cobalt-substituted CPase Taq did not affect the enzyme activity, it could act as the natal metal ion in the active center of the enzyme.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.677-682
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• 2006

Dodecyldimethylethylammonium (DDDEA), a cationic surfactant, and aluminum metal ions were used with bentonite to synthesize to synthesize an improved organo bentonite. Among three different synthesis procedure for organo bentonites, aluminium-pillared bentonite showed the highest DDDEA sorption, which indicated that aluminium-pillared organo bentonite would exhibit the highest sorption capacity for organic contaminants. Aluminium pillared organo bentonite also showed a high sorption capability for phosphorus, while it did not exhibit strong sorption for nitrate. In the meantime, more desorption was observed with aluminium-pillared organo bentonite than ordinary organo bentonites.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.181-188
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• 2013

The effect of transition metal ion exchange into UZM-9 zeolite with LTA framework on its deactivation in methanol-to-olefin (MTO) conversion was discussed. The ion exchange of copper, cobalt, nickel, and iron did not induce any notable change in the crystallinity, crystal morphology, and acidity of UZM-9. The small cage entrance of UZM-9 caused the high selectivity to lower olefins in the MTO conversion, while its large cages allowed the rapid further cyclecondensation of active intermediates, polymethylbenzenes including hexamethylbenzene, resulting in a rapid deactivation. The UZM-9 containing copper and cobalt ions showed considerably slow deactivations. The interaction between transition metal ions and polymethylbenzene cation radicals, the active intermediates, generated in the MTO conversion stabilized the radicals and slowed down the deactivation of UZM-9.

• Journal of Food Hygiene and Safety
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• v.15 no.2
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• pp.176-178
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• 2000

V parahaemolyticus possessed an extracellular alkaline pretense activity during the stationary growth phase. Various factors such as nitrogen sources, the concentration of NaCl and metal ions were investigated for optimizing the production of alkaline pretense from V. parahaemolyticus ATCC 17802. Among the nitrogen sources tested skim milk showed the distinct increase of the activity and the activity was the highest at 2% in final concentration after 60 hours incubation. The addition of NaCl and metal ions did not increase the alkaline pretense activity. CoC$_2$, CuC1$_2$, and HgCl rather highly inhibited alkaline protease production.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.696-702
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• 1998

The effect of alkali metal salt on the activity of Co-Mo catalyst which has high resistance to sulfur poisoning for water gas shift reaction(WGSR) was studied. Two groups of catalysts were prepared to investigate the effects of anion and cation in alkali metal salts. For K-doped catalysts made with various potassium salts having different anion, the catalytic activity was explained to depend mainly on the BET surface area. Among the catalysts prepared by various nitrates of alkali metal as precursor, the Li-doped catalyst showed the best activity, and the others did not make significant differences giving relatively low activities. And the change of BET surface area by varying the loading of alkali metal showed a similar trend to that of activity. In this case, the activity was dependent on both BET surface area and the ratio of $Mo^{6+}$ with a tetrahedral coordination symmetry to $Mo^{6+}$ with an octahedral one, $Mo^6+[T]/Mo^{6+}[O]$ value.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.533-540
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• 2010

An activated carbon was tested for its ability to remove transition metal ions from aqueous solutions. Physical, chemical and liquid-phase adsorption characterizations of the carbon were done following standard procedures. Studies on the removal of Ni(II), Cu(II) and Fe(III) ions were attempted by varying adsorbate dose, pH of the metal ion solution and time in batch mode. The equilibrium adsorption data were fitted with Freundlich and Langmuir and the isotherm constants were evaluated, equilibrium time of the different three metal ions were determined. pH was found to have a significant role to play in the adsorption. The processes were endothermic and the thermodynamic parameters were evaluated. Desorption studies indicate that ion-exchange mechanism is operating.

• Clean Technology
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• v.22 no.3
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• pp.161-167
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• 2016

Catalytic combustion of benzene over various metal cation-exchanged zeolites has been investigated. Y(4.8)-type zeolite showed the highest activity among the used zeolites and Cu/Y(4.8) catalyst also showed the highest activity among metal cation/ Y(4.8) zeolites. The catalytic activity increased according to the amount of adsorbed oxygen acquired from O₂ TPD results. The catalytic activity also increased with an increase of Cu cation concentration on Cu/Y(4.8) catalysts. The conversion of benzene on the combustion reaction depended on not benzene concentration but the oxygen concentration. In addition, the introduction of water into reactants decreased the catalytic activity.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.109-117
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• 1996

Removal of metal ions on the ultrafiltration membrane with micellar-enhanced with anion surfactants is a recently developed technique which can remove heavy metals and small molecular weight ions from wastewater with simple separation process and without a phase change. Above a certain concentration, so called the critical micelle con binding cationic cobalt ions and anionic surfactants, were removed by ultrafiltration membrane. The transmembrane pressure difference had a relatively small effect on the rejection coefficient of metal ions on the ultrafiltration membrane whereas the level of anionic surfactant-to-metal ratio (S/M) had a substantial effect.

• KSBB Journal
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• v.16 no.1
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• pp.54-60
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• 2001

The activity of microorganisms is an important factor that determines the efficiency of the bacterial recovery of precious metals from low-grade ore. Metal-leaching microorganisms must have a tolerance, within the concentration levels encountered to leached metals. In this study, the tolerance levels of Thiobacillus ferroxidans to the single and mixed metal ions systems, composed of $Zn^{2+}$, $Cu^{2+}$, $Ni^{2+}$, and $Cd^{2+}$ were investigated. When single metal ions of $Zn^{2+}$ (10~60 g/L), $Cu^{2+}$ (1~6 g/L), $Ni^{2+}$ (1~6 g/L), or $Cd^{2+}$ (1~6 g/L) were added to the growth medium of T. ferrooxidans, the iron oxidation rate of this bacterium was not significantly inhibited. The maximum inhibition percentage observed on the iron oxidation rate of T. ferrooxidans was approximately 50% in the medium supplemented with two or three mixed metal ions of $Cu^{2+}$, $Ni^{2+}$, and $Cd^{2+}$. However, when $Zn^{2+}$ was also added to the medium with the other metal ions, the inhibitory effect on the iron oxidation activity of T. ferroxidans was remarkably increased.

• Journal of the Korean Chemical Society
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• v.27 no.2
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• pp.127-132
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• 1983

The catalytic activity of ZSM-5 catalyst for the disproportionation of toluene is dependent on the type of cation exchanged, the degree of ion-exchange and the reaction temperature. The activity increases in the order of alkaline-, alkali earth-, hydrogen, and rare-earth-exchanged ZSM-5 and decreases with increasing degree of cation exchange. Among the ion-exchanged ZSM-5 catalyst, only Cs-ZSM-5 shows predominant selectivity for p-xylene. The selectivity increases with increasing degree of $Cs^+$-exchange and decreasing reaction temperature. This phenomenon is interpreted in terms of shape selectivity arising from the partial blocking of channel intersections by large cesium ions.